The invention relates generally to pneumatic fluid control valves, such as the type used for controlling the flow of pressurized air as a pneumatic working fluid to and from a pneumatically-actuated drive cylinder device, which in turn is used to drivingly actuate a machine or other apparatus. More specifically, the invention relates to such pneumatic control valves that are capable of efficient, fast-acting operation with substantially no internal leakage of pneumatic working fluid.
It is well-known to use pneumatic control valves for controlling the operation of pneumatic fluid-actuated drive mechanisms, such as pneumatic cylinder-and-piston devices used for driving various types of machines or apparatuses, such as presses, process or assembly line devices, or any of a wide variety of other well-known tools or equipment. Such pneumatic fluid control valves are typically required to operate rapidly, slidably and precisely over millions of operating cycles during the lives of the valves themselves and the equipment they are used to control. In addition, due to energy efficiency requirements, precision operating parameters, requirements relating to ambient plant conditions, or other design considerations, such valves are often required to operate with low or minimal, internal leakage of pneumatic working fluid. Although these requirements have been generally well-served by a wide variety of configurations or types of pneumatic fluid control valves currently in use, ever-increasing technological demands, have given rise to the need for even greater levels of performance of such valves.
Accordingly, in accordance with the present invention, a pneumatic fluid control valve apparatus capable of even faster and more precise operation, as well as even lower, near-zero internal working fluid leakage, is provided. A pneumatic fluid control valve apparatus according to the present invention typically includes a valve body portion having a working fluid inlet connectable to an external source of pressurized pneumatic working fluid, one or more working fluid load outlets, one or more corresponding exhaust ports, and a movable valve mechanism disposed within the valve body. The control valve apparatus is connectable to a conventional pilot operator adapted for selectively applying pneumatic fluid pressure to the movable valve mechanism in order to communicate one of the load outlets first with the working fluid inlet and then with a corresponding exhaust port, thus alternately causing pneumatic working fluid to be transmitted to and from a drive actuator device.
The movable valve mechanism of the present invention preferably includes a first movable valve element movably located within a first chamber in the valve body, with the first chamber being in communication with a first working fluid load outlet and a first corresponding exhaust port. A second movable valve element is movably located within a second chamber within the valve body, with the second chamber being in communication with the first chamber, with the working fluid inlet, and with the first working fluid load outlet. The movable valve mechanism may also include a third movable valve element movably located within a third chamber in the valve body portion, with the third chamber being in communication with the second chamber, with a second working fluid load outlet, and with a second corresponding exhaust port. A deformable connector is disposed with the valve body in a generally abutting relationship between the first and second movable valve elements, and a second deformable connector may be disposed between the second and third movable valve elements (if so equipped) for deformably transmitting a coordinated or responsive motion therebetween. A pair of pistons disposed at opposite ends of the valve body portion abuttingly engage the first and second (or the first and third) movable valve elements, respectively, in order to impart such coordinated motion to the movable valve mechanism, thereby selectively communicating the working fluid inlet with one or the other of the working fluid load outlets and to communicate the opposite working fluid load outlet with exhaust.
In a preferred form of the present invention, the deformable connectors are arranged in a substantially straight, linear in-line orientation along the paths of movement of the movable valve elements, which are preferably of a spherical (or at least partially spherical) arcuate shape, at least in the portions that are adjacent their respective valve seats within the valve body. Also in a preferred form of the invention, such deformable connectors are resiliently deformable coil springs, although other resiliently deformable connector configurations can also be employed. The preferred resiliently deformable connectors each resiliently compress to allow one of its adjacent movable valve elements to move a considerable amount before transmitting such coordinated motion to the other of its adjacent movable valve elements in order to move it to the opposite end of its travel.
In addition, in order to minimize wear on the movable valve elements, the preferred coil spring connectors have their ends ground to a generally-spherical, concave arcuate shape that is complementary to the arcuate spherical surface of the adjacent preferred movable valve elements mentioned above.
Such preferred construction of the pneumatic fluid control valve apparatus according to the present invention offers distinct advantages in terms of speed and precision of operation, as well as eliminating, or at least substantially minimizing, undesirable internal cross-over leakage of pneumatic fluid during movement of the valve elements. It should also be noted that the invention can be applied advantageously in a variety of control valve types, including three-way valves, four-way valves, dual three-way valves capable of acting either in parallel or as a four-way valve, as well as in other configurations that will readily occur to those skilled in the art.
Additional objects, advantages, and features of the present invention, however, will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.